In thermal printing, it is generally well known to render images by heating and pressing one or more donor materials such as a dye, colorant or other coating against a receiver web. The donor materials are provided in sized donor patches on a movable web known as a donor ribbon. The donor patches are organized on the ribbon into donor sets; each set containing all of the donor patches that are to be used to record an image on the receiver web. For full color images, multiple color dye patches can be used, such as yellow, magenta, and cyan donor dye patches. Arrangements of other color patches can be used in like fashion within a donor set. Additionally, each donor set can include an overcoat or sealant layer.
Thermal printers offer a wide range of advantages in photographic printing including the provision of truly continuous tone scale variation and the ability to deposit, as a part of the printing process a protective overcoat layer to protect the images formed thereby from mechanical and environmental damage. Accordingly, the most popular photographic kiosks and home photo printers currently use thermal printing technology.
Electrostatic charge can be generated in thermal printers by peeling donor media from receiver media. Electrostatic charge is a significant concern and problem for makers of thermal printers, because excess static charge leads to jamming and buckling of print media as the print media traverses through the thermal printer. Conventional approaches to addressing static charge focus on the media itself in that, ionic or nonionic anti-stats are added to the media; for example, the receiver media. This anti-static material is adjusted positionally to reduce static charge. In other words, the anti-static material may be placed in multiple locations with varying effectiveness. The anti-stats may be placed in various layers of the receiver and donor media.
Limitations of anti-stats include, for ionic anti-stats, their ineffectiveness in high humidity. Both ionic and non-ionic anti-stats are subject to great expense, and imprecise usage that is dependent upon the receiver media impacted with reduction of static charge. Another disadvantage associated with non-ionic anti-stats is an addition of unwanted color in white areas of a print.